Polycrystalline diamond (PCD) material comprises a mass of inter-grown diamond grains and interstices between the diamond grains. PCD material may be made by subjecting an aggregated mass of diamond grains to a high pressure and temperature in the presence of a sintering aid such as cobalt, which may promote the inter-growth of diamond grains. The sintering aid may also be referred to as a catalyst material for diamond. PCD material may be formed on a cobalt-cemented tungsten carbide substrate, which may provide a source of cobalt catalyst material for sintering the PCD material.
PCD material may be used in a wide variety of tools for cutting, machining, drilling or degrading hard or abrasive materials such as rock, metal, ceramics, composites and wood-containing materials. For example, tool inserts comprising PCD material are widely used in drill bits used for boring into the earth in the oil and gas drilling industry. In many of these applications, the temperature of the PCD material may become elevated as it engages rock or other workpiece or body with high energy. The working life of tool inserts may be limited by fracture of the superhard material, including by spalling and chipping.
In use as a cutting element in tools such as those mentioned above, the body of PCD material normally wears according to the following progression: smooth wear, woody wear, accelerated wear, spalling. Spalling usually occurs when the wear scar reaches the top working surface, and results in catastrophic wear failure.
As used herein, the term “barrel chipping” refers to chipping in the body of PCD material below a main wear-scar.
Smooth wear as used herein refers to wear occurring at the diamond grain level where individual grains or fractions of grains are removed.
Woody wear as used herein refers to the regime where the wear-scar becomes irregular at the edges and cracking visible. The rough appearance of the wear-scar is possibly due to wear processes at a scale of more than one grain.
As used herein the term spalling refers to catastrophic failure due to wear cracks propagating to top of the PCD body acting as a cutter table.
Durability here refers to distance cut before cutter failure. High-durability cutters tend to maintain cutting integrity but eventually become ineffective due to formation of a very large wear-scar and hence impractical load application requirements. Prevention of spalling would increase lifetime/durability of the cutter and there is therefore a need for a product in which spalling is partially or completely inhibited and a method of producing such a cutter.